1. Field of the Invention This invention relates generally to inch calculators, having as its particular object an improved inch keyboard designed to work in sequence with any functionally adaptable inch calculator.
2. Technical Considerations and Prior Art The input data for inch calculators consist of measure numbers and measuring units, standing for the linear dimensions of technical drawings.
In fact, the dimension is a juxtaposition of three portions, measured in the distinct species of the units they include, and termed here sub-dimensions:
Number of Feet, PA0 Number of Inches, and PA0 Number of Equal Parts of an Inch Fraction. PA0 1978, Goldsamt et al. U.S. Pat. No. 4,081,859. PA0 1978, Boyd, U.S. Pat. No. 4,100,603. PA0 1984, Lipsey et al. U.S. Pat. No. 4,488,250 PA0 1985, Hughins, U.S. Pat. No. 4,545,022. PA0 1988, Stover et al. U.S. Pat. No. 4,744,044. PA0 1992, Comforti, U.S. Pat. No. 5,138,566. PA0 Prod. #3170 Calculated Industries, Pocket Handyman II PA0 3 measure numbers, PA0 [2][10][13]. PA0 The Nine-Lane, for 1 Ft to 1/128" range of units, and PA0 The Six-Lane, for 1 Ft to 1/16" range.
Because each sub-dimension is: EQU (a measure number).times.(a measuring unit),
it results, without exception, that the inch calculators must perform the handling of six distinct data per handled dimension: EQU (3 numeric data)+(3 unit species)
and the only in which the inch calculators can compete for performance is in the ways they deal with the species of units.
The performance of inch calculators is directly conditioned by their keyboards and may be compared by the number of keystrokes KS each one requires for the entry of the same dimension. For example, of: EQU 2 Ft-10 In-13/16.
where 2, 10 and 13 are the measure numbers of the subdimensions 2 ft, 10 In and 13/16. To evaluate the level of the prior art, we will use this example and the KS criterion to compare a number of known inch calculators:
Lacking the sixteenths. Not comparable. PA1 Having only the 1/16" as fraction. Not comparable. PA1 [2],[Ft],[1],[0],[In],[1],[3],[x/16]. PA1 [2],[Ft],[1],[0],[AND],[1],[3],[1/16]. PA1 [2],[Ft],[1],[0],[IN],[1],[3],[/],[1],[6]. PA1 Lacking the Feet. Not comparable. PA1 [2],[Ft],[1],[0],[IN],[1],[3],[/],[1],[6].